I've always felt pretty small, and when I think more about it, very insignificant. I'm just one person among billions. This is one planet among 8 (I almost typed 9 there >_>). This is one star system among billions. And this is one galaxy among, well, A LOT.

And there's so much more we can't see at the moment. Of course this allows for the possibility of life on other planets, seeing as how there's so much we can't see that we can't just totally cross out the chance of life. The universe is so vast that it would be pretty much impossible that there isn't life on other planets.